Lifting-jack



G. BROCKE.

LIFTING JACK- APPLICATION FILED FEB. 26, 1920.

Patented Feb UNITED STATES PATENT OFFICE.

GERHARD BROOKE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR OF ONE-THIRD T0 WILLIAM J. HOLD, OF CASTLE SHANNON, PENNSYLVANIA, AND ONE-THIRD TO GEORGE C. FEUCHT, OF PITTSBURGH, YENNSYLVANIA.

LIFTING-JACK.

' Specification of Letters Patent.

Patented Feb. 8, 1921.

Application filed February 26, 1920. Serial No. 361,580.

To all whom 2'25 may concem:

Be it known that I, GERHARD BROOKE, re

siding at Pittsburgh, in the county of A llegheny and State of Pennsylvania, af c1t1z en of the United States,have invented or (llS- covered certain new and useful Improvemerits in Lifting-Jacks, of which improvements the following is a specification.

My invention relates to improvements 1n lifting jacks built on the principle of the hydraulic press and involving an appl1cation of Pascals law. It is illustrated in the accompanying drawings.

Figure I is a view in vertical section of a lifting jack embodying my invention, and showing in elevation the screw which forms part of the structure; Fig. II is a fragmentary view to larger scale but on the same plane, and in this View the screw also 18 shown in section; Fig. III is a view partly in plan and partly in horizontal section of a.portion of the structure, and as Wlll be noted the sectional showing which this figure aflords is found in two different planes. Fig. IV is a view in section of a portion of the structure on a vertical plane at an angle to that of Fig. I, and on Figs. I and IV are indicated by the dotted lines IIII II the planes of the partial sections shown in Fig. 1H. Fig. V shows partly in end elevation, partly in section on the plane indicated by the line VV, the assembled parts shown in Fig. II. Figs. VI and VII are views in section on the planes indicated by lines VI-VI and VII -VII, Fig. II.

This lifting jack includes two connected cylinders, 1 and 2, conveniently organized as shown; cylinder 1 constitutes a base block for the structure as a whole, and cylinder 2 is tapped into the wall of cylinder 1, conveniently at an angle, to afford clearance for application of power, as will presently appear. The screw-thread union of the two cylinders may be rendered more certainly fluid-tight by means of packing 12 clamped between abutting faces. A duct 3 brings these two cylinders into communication. Within cylinder 1 is a piston which takes the form of a ram 4, and is the work-sustaining member, and within cylinder 2 is a piston 5, to which power is applied. By making cylinder 1 of relatively large and cvlinder 2 of relatively small diameter, Pascals law is realized, and power applied to piston 5 is communicated through the body of liquid which fills the cylinders beneath the pistons and the duct through which connection is maintained, and is applied to ram 4, magnified according to the ratio by which the area of the ram within cylinder 1 exceeds the area of piston 5 within cylinder 2. The first feature of invention to which-I direct attention is the packing collar with which each of the two pistons is provided. It will suffice to describe this collar in its application to the piston 5 in the power cyllnder; the reader will understand, and the drawings show, that a like collar is applied to the piston in the work cylinder, the ram 4. The collar is of flexible material, ordinarily of leather and so adapted to be brought into close and extended contact with the inner surface of the cylinder. This flexiblecollar takes the form of a leather cup 6, of substantially equal diameter with piston 5 itself, and it is secured to piston 5 in the outwardly flaring position, shown most clearly in Fig. II, by means of the binding nut 7 which screws upon a stud 8 formed on the face of piston 5 and which when applied clamps the cup 6 to the piston 5. A central hole formed through the cup allows it to pass over stud 8 and come to position upon the face of piston 5. A washer 9 may be interposed between the central web of cup 6 and the binding nut 7. Means are provided for impelling the flange of cup 6 outward when the piston is assembled in its cylinder, and pressing it into closer contact with the interior face of the cylinder. Such means conveniently take the form of an expansible circular spring 10, conveniently carried in a groove in a suitably disposed portion 11 of the body of nut 7. I

The particular construction by which a like collar is secured to ram 4 may be so far particularly alludedto, in order to note that in this instance the ring 10 is carried in a groove in a flange formed in washer 9, instead of in a groove in the body of nut 7. The cylinders beneath the pistons and the connecting duct 3 are, it will be understood, filled with liquidoil, or another suitable liquidand the filling will be done initially when the parts are first assembled. In the course of service, however. the liquid will gradually be wasted or defiled and replen ishment or replacement will at times be desired. The packing too will in time require replacement, though in this respect my device is vastly superior to any other of like type of which I have any knowledge. To 5 permit of these things, aswell as to facilitate the initial assembly, a duct for the passage of oil leads to the space contained between the two pistons, and this duct becomes part of a filling port. The particular place where this filling port is located may vary; conveniently it is located, as shown, in the base of cylinder 1. A chambered plug 13. with an opening or openings letextending through its face from its chambered interior, is tapped-into a suitable seatin the cylinder wall, and from the base of this seat a duct 15 leads to the interior of cylinder 1. The openings 14 through the plug and the duct 15 are, when the parts are assembled, out of alinement; in this case the duct 15 leads centrally from the seat while the openings 14 open at a distance from the center of the plug. The seat for the plug may be faced with a perforate disk 16 of suitably elastic material. The chamber within plug 13 is screw-threaded to receive connection from instrumentalities for emptying and filling. Further description is unnecessary to show that the plug 13 constitutes a valve, closing and opening (as it is turned), duct 15, and it will beunderstood further that, when proper connection. has been made and plug 13 has been turned, the space between the pistons may besubstantially evacuated and I filled with a. fresh quantity of fluid, or, when preferred, the existing body of fiuid may be augmented merely, with the fresh supply.

In addition to the cylinders with their pistons, and the filling port, the structure in- 4O cludes a screw, which is the power-applying member, for driving piston 5 in cylinder 2.

In the outer end of cylinder 2 is secured in suitable manner, as by screw-thread and setscrew shown, a block 26, and this block 15 provided with an axial screw-threaded bore,

in .which turns the screw 17, and screw 17 as it turns moves longitudially of the cylinder. The outer end of screw 17 is shaped for the a lplication of power, as exemplified in the poygonal head 18, adapted to be engaged by a wrench.

The connection of screw 17 to piston 5 is such that the full force of the power applied shall be exerted to drive piston 5, and while thetwo members are so connected as to move in and out, longitudinally of the cylinder, in unison, piston 5 shall not turn with the turn ingot the screw, but to the contrary shall to.

the farthest extent be relieved of all strain of turning. T hus'the packing is relieved of all unnecessary wear. To efi cct these ends piston 5 is provided with an outward-extending cage, preferably an. open-ended cylindrical extension 19. Into this cage the end of 6 screw 17 extends. The thrust of the inward I driven screw 17 is imparted to piston 5 through the balls 20 carried in a suitable frame 21, borne upon by the end of the screw and bearing upon piston 5 preferably I through a disk of tool steel 22. The frame 2l'consists of two plates riveted together and provided with corresponding perforations which enlarge in diameter inwardly, that is to say toward one another. Thus the two plates constitute a retainer which being closed upon the balls holds them secure and in proper relative positions, allowing them at thesame time freedom of rotation. Indeed the whole structure floats between the end of screw 17 and piston 5.

The extreme end of screw 17, extending int-o the cage 19 iscylindrical. In the face of this cylindrical extension is cut an encircling groove 23, and pins 24 set in suitable holes drilled in cage 19 connect piston 5 and screw 17 together in such manner as to allow free independentturning of screw 17 but to insure longitudinal movement in unison of the connected parts. It will be particularly noted in Fig. II that the groove 23 is slightly elongated-there is a slight range of play in the connection here-to the end that all of the thrust of driving may be exerted through the balls 20 and none through the pins 24.

In operation it will be understood that the advance and retraction of screw 17 will effeet a corresponding rise and fall of ram 4.

The connection between screw 17 and pis ton 5 particularly described above is such as to relieve cup 6 of twisting strain, which otherwise would soon disrupt it and impair the apparatus.

The jack is of particular value in raising end trucks on traveling cranes, and generally in places where space is not suflicient to per mit the use of more cumbersome apparatus.

In the ensuing claims I define the essential features of my invention. Beyond what is there defined the showing of the specification is exemplary and variation is permissible.

I claim as my invention:

1. A lifting jack including in its structure a work cylinder and a power cylinder in communication one with the other, a piston in each cylinder, the space Within the cylinders and between the two pistons adapted to be filled with liquid, a driving screw entering said power cylinder and engaging the piston therein in an engagement permitting a limlted'independent movement of screw and piston longitudinally of the cylinder, and bearing balls interposed between the end of the driving screw and the opposed surface of the piston, substantially as described.

2. A lifting jack including in its structure two comn'iunicating cylinders, a piston in each cylinder, a screw entering one of said cylinders and abutting upon the piston therein, a cage formed upon the piston last mentioned into which said screw extends to make such abutment, a groove encircling the screw within such cage, a pin borne by said cage and extending into said groove, said groove being of greater dimension longitudinally of the screw than the thickness of the pin, and a ball-bearing structure arranged between piston and screw, substantially as described.

' 3. A lifting jack including in its structure two communicating cylinders with a piston ineach, and means for applying power to one of said pistons, a filling port leading to the communicating space between the pistons and including a socket, a duct leading from said socket to the space to be filled, a chambered plug screw-threaded into said socket, and a passageway through said plug out of axial alinement with said duct, substantially as described.

In testimony whereof I have hereunto set my hand.

' GERHARD BROOKE. Witnesses:

FRANCIS J. TOMASSON, FRANCIS J. BEVILACQUA. 

